At 2:32 PM -0500 12/31/2001, Barrie Robinson wrote:
>I ran an MGB GT for 8 years here in Canada in summer and winter and I do
>not drive "soft" but neither do I thrash the engine. The car's body
>collapsed under the weight of rust but the engine went into my friends car
>and is still smooth, lusty and pulls hard (sound like a girlfriend I
>had). It never saw leaded fuel! I then tested Shell Canada unleaded
>over a years driving an Austin Healey - they paid for everything. The
>engine was measured with a special jig made by Shell to determine wear -
>result? no signs of valve seat recession. I believe that hardened seats
>are great but not always required - unless you intend to thrash the engine
>(in which case something else will give too).
>
>At 11:52 AM 12/31/01 -0600, Rocky Frisco wrote:
>>Lawrie Alexander wrote:
>> >
>> > Maynard, Maynard, Maynard............
>> >
>> > So much good advice from your keyboard this year, and then you wait
>> till the
>> > very end to post this! Empirical tests have proven that hard seats prevent
>> > valve seat recession. Just about every qualified mechanic who
>>has worked on
>> > cars that were not originally fitted with hard seats knows that they are
>> > necessary to prevent valve seat recession. The additional cost during a
>> > valve job is so small that, unless the finished rebuild is going to sit
>> in a
>> > trailer queen that never gets used, it's truly false economy not
>>to have it
>> > done.
>> >
>> > I hate to close the year on a critical note, but hardened exhaust valve
>> > seats are a must when doing a valve job - if they have not already been
>> > fitted during prior work on the engine. You may choose, of course, for
>> > whatever reason, to find them unnecessary, but please don't try and
>> convince
>> > other neophytes to the world of engine rebuilds that your choice is the
>> most
> > > sensible!
>>
Maybe I've just been unlucky, but I've rebuilt two high mileage heads
in the past 5 years. In each case there were over 100,000 miles on
the engine. I do drive a bit hard (auto crossing, high speed touring
and such) and frequently drive on long trips often from 3000 to 5000
miles. In each case the exhaust valves had receded into the head
markedly!
I'm with Lawrie on this one.
--
Bob Shaw
Check out Shaw's Garage at http://www.mlcltd.com/shawsgarage/
My British Car is NOT leaky - it's merely marking its territory.
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